|A friend has also sent the work by Boys in which Braun's researches are favourably mentioned. He responds to Boys querying preferences between the oscillation method and the deflection method. He is continuing with his researches after having had problems with the lever, where poor soldering meant that pieces of aluminium had shifted. Today he has made first observations on determining the momentum of inertia. Braun is working to make his air-pump airtight and gives a sketch of the arrangement. In general his labours are going well, if slowly.